1. Field of the Invention
The present invention relates generally to paper or like material handling machines and more particularly to a device and method for remotely advancing sheets.
2. Background Information
Sheets of material, for example printed sheets of paper, often are stacked and fed by belts to processing machines, such as folding machines which take individual sheets of paper from the stack and fold them. The lead edge of the stack often is used to activate a switch, which controls the feed or motion of the stack.
U.S. Pat. No. 4,600,185 purports to disclose an apparatus for detecting and actuating the feeding of paper in paper folding machines. A scanning head positioned adjacent to an underside of the paper load reads the paper load from the bottom. The scanning head is located on an upper end of an arm which is adjustable through the movement relative to two perpendicular shafts. The scanning head can provide a signal to control the paper feed.
This patent has the disadvantage that a scanning head is used to sense the paper edge, which can malfunction due to dust or other contamination blocking the scanning head. Moreover, the positioning of the scanning head requires the operator to place hands near the feeding mechanism, which can be inconvenient and require that the operator reach under the scanning head. The nuts used to position the scanning head also might move due to vibrations of the machine, causing the position of the scanning head to be altered.
An object of the present invention is to provide a method and device for reliable advancing of sheets. Another additional or alternative object of the present invention is to provide for a feed finger which can be easily positioned.
The present invention provides a sheet advance device comprising a transport device for transporting a stack of sheets in a first direction; a feed finger located in the path of the stack of sheets for contacting the stack of sheets; and a sensor for detecting a movement of the feed finger. A position of the feed finger is adjustable by an adjustment device located externally with respect to a frame of the sheet advance device.
Since the adjustment device is located remotely from the feed finger, an operator advantageously may adjust the feed finger positioning from the frame or from beyond the frame without have to reach within the sheet advance device.
The feed finger preferably is supported on disk mounted rotatably on a support assembly, the support assembly including two perpendicular slideways for positioning the disk. The adjustment device preferably includes two knobs located on an outer surface of the frame, and two flex shafts connect the two knobs to the two slideways.
The feed finger and disk may be spring-loaded in a direction opposite the first direction.
The sheet advance device of the present invention provides that physical contact by the sheets triggers the feed finger, which is easily positioned without having to reach inside the device. As individual sheets of the stack are removed, the spring-loading moves the feed finger opposite the first direction, thereby triggering the transport device to move in the first direction.
The sensor preferably includes a sensor plate connected to the disk and a proximity switch located next to the sensor plate. When the sensor plate touches the proximity switch, belts of the transport device on which the sheets are located can be stopped. As the individual sheets are removed from the stack, the disk, which is spring-loaded, can rotate so that the sensor plate again moves away from the proximity switch, and the belts can be moved again.
Adjustment of the position of the feed finger can be achieved by the two slideways, one of which is preferably in a horizontal plane and the other in a vertical plabe. By adjusting the position of the feed finger, fine positioning of the stack with respect to a removal device, for example a suction wheel, can be achieved.
The present invention also provides a method for advancing sheets on a transport device comprising the steps of:
moving a stack of sheets on the transport device against a feed finger so as to move the feed finger in a first direction;
sensing the movement of the feed finger so as to generate a stop signal;
stopping the transport device as a function of the stop signal;
removing individual sheets from the stack of sheets so as to reduce the stack in a direction opposite the first direction and move the feed finger opposite the first direction;
moving the transport device in the first direction after the removing step; and
adjusting a position of the feed finger through an externally-located adjustment device.
The feed finger preferably is spring-loaded to move opposite the first direction. The feed finger may be located on a rotatable disk, with a sensor sensing a rotation of the disk to generate the stop signal.
The transport device preferably includes at least one belt.